I installed PHC-Intel 0.3.2.12.1-r5 through Gentoo's portage. The module loaded fine, and I got the various devices, but changing the VID values seemed to have absolutely no effect. So I decided to try the newer rev 9.1 PHC-Intel also available on this site. I compiled the program, and I got the same results with both "make brave" and "make canny". When I ran "insmod phc-intel.ko", I got the message "insmod: ERROR: could not insert module phc-intel.ko: Unknown symbol in module". The output of dmesg showed "phc_intel: Unknown symbol cpufreq_get_measured_perf (err 0)".

I am using the Gentoo patched 3.9.2 kernel with the latest CK and BFQ patches applied. I used gcc 4.8.0, binutils 2.23.1, and glibc 2.17. I'm using a Dell Latitude D620 laptop. This is the output of "cat /proc/cpuinfo":

PaddyMac wrote:I installed PHC-Intel 0.3.2.12.1-r5 through Gentoo's portage. The module loaded fine, and I got the various devices, but changing the VID values seemed to have absolutely no effect.

How to you know it has no effect? Whats in your /sys/devices/system/cpu/cpu*/cpureq/phc_vids and phc_default_controls? Does your system crash when you undervolt too much (especially for the highest core frequency)?

So I decided to try the newer rev 9.1 PHC-Intel also available on this site

There is no big difference in rev9.1 over any other 0.3.2-version. It's only minor tweaks to get the stuff compiled for newer kernel versions but no functional enhancements. So if the version from Gentoo does compile and it is not working, revX probably won't do any better.

"phc_intel: Unknown symbol cpufreq_get_measured_perf (err 0)"

Have a look at the version of acpi-cpufreq-c in gentoo and compare it to the version shipped with phc-intel-rev9.1. Do they differ? rev9.1 shipps with vanilla sources and assumes that mperf is available built in or as module.